1. Field of the Invention
This invention relates generally to voice/data communications systems and in particular to apparatus and techniques for a digital voice storage and retrieval system adapted for use in a multi-unit land mobile radio communications system.
2. Description of the Prior Art
The prior art includes various types of radio frequency transmission systems of the general type which serve to effect a selective transmission from or to an emergency vehicle or purposes of generating a warning transmission. Conventional systems typically utilize magnetic tape or wire for the storage of the desired message and utilize conventional playback arrangements. However, use of such conventional systems in many applications present substantial difficulties due to the environment, weight, and size limitations imposed by such applications. In addition, automatic record and playback devices are known in the prior art, such as with telephone answering systems, that answer with recorded instructions on a first magnetic tape, then record a telephone message on a second magnetic tape. Somewhat similar systems for recording a received message at a mobile or pre-recording a message to be transmitted in response to remote activation, are utilized in multi-unit mobile radio communications systems. These electromechanical systems are typically bulky, unreliable, and inflexible. Also, these prior art arrangements only provide sequential access for generating fixed messages. Therefore, many potential applications have not been feasible in the prior art due to the limitations of these systems.